Revert "Add PolyGerrit UI for configuring uploadvalidator"

This reverts commit dfbdc0ef156ca3bb21d7de95428dbca05f533b07.

This also reverts fixes that were made to these UI components.

From version 3.0 onwards, project configuration menus for plugins
are again automatically created. Thus, the custom menu is removed
with this change.

Bug: Issue 12082
Change-Id: I08cbe62dd72e88f7a1ec144f691468449008278d
7 files changed